Chronic inflammation, chronic obstructive pulmonary disease, and lung cancer

What to do when a smoker's CT scan is "normal"?: Implications for lung cancer screening

Lung cancer is the leading cause of cancer-related mortality in the United States and around the world. There are > 90 million current and ex-smokers in the United States who are at increased risk of lung cancer. The published data from the National Lung Screening Trial (NLST) suggest that yearly screening with low-dose thoracic CT scan in heavy smokers can reduce lung cancer mortality by 20% and all-cause mortality by 7%. However, to implement this program nationwide using the NLST inclusion and exclusion criteria would be extremely expensive, with CT scan costs alone > $2 billion per annum. In this article, we offer a possible low-cost strategy to risk-stratify smokers on the basis of spirometry measurements and emphysema scoring by radiologists on CT scans.

Multistage analysis of variants in the inflammation pathway and lung cancer risk in smokers

BACKGROUND

Tobacco-induced lung cancer is characterized by a deregulated inflammatory microenvironment. Variants in multiple genes in inflammation pathways may contribute to risk of lung cancer.

METHODS

We therefore conducted a three-stage comprehensive pathway analysis (discovery, replication, and meta-analysis) of inflammation gene variants in ever-smoking lung cancer cases and controls. A discovery set (1,096 cases and 727 controls) and an independent and nonoverlapping internal replication set (1,154 cases and 1,137 controls) were derived from an ongoing case-control study. For discovery, we used an iSelect BeadChip to interrogate a comprehensive panel of 11,737 inflammation pathway single-nucleotide polymorphisms (SNP) and selected nominally significant (P < 0.05) SNPs for internal replication.

RESULTS

There were six SNPs that achieved statistical significance (P < 0.05) in the internal replication data set with concordant risk estimates for former smokers and five concordant and replicated SNPs in current smokers. Replicated hits were further tested in a subsequent meta-analysis using external data derived from two published genome-wide association studies (GWAS) and a case-control study. Two of these variants (a BCL2L14 SNP in former smokers and an SNP in IL2RB in current smokers) were further validated. In risk score analyses, there was a 26% increase in risk with each additional adverse allele when we combined the genotyped SNP and the most significant imputed SNP in IL2RB in current smokers and a 36% similar increase in risk for former smokers associated with genotyped and imputed BCL2L14 SNPs. CONCLUSIONS/IMPACT: Before they can be applied for risk prediction efforts, these SNPs should be subject to further external replication and more extensive fine mapping studies.

Suppressive effects of a pyrazole derivative of curcumin on airway inflammation and remodeling

To advance the control of airway epithelial cell function and asthma, we investigated the effects of a new curcumin derivative, CNB001, which possesses improved pharmacological properties. Normal human bronchial epithelial (NHBE) cells were stimulated with synthetic double-stranded RNA, Poly(I:C). CNB001 significantly suppressed IL-6, TNF-α, and GM-CSF production by NHBE cells, and did so more effectively than did curcumin or dexamethasone (DEX). CNB001 significantly inhibited the decrease of E-cadherin mRNA expression and increase of vimentin mRNA expression observed in NHBE cells induced by a combination of TGF-β1 and TNF-α, which are markers of airway remodeling. In NHBE cells stimulated by TGF-β1, CNB001 significantly downregulated the level of active serine peptidase inhibitor clade E member (SERPINE) 1, which is also reported to be related to airway remodeling. Whereas DEX alone significantly increased the active SERPINE1 level, the combination of DEX and CNB001 significantly suppressed active SERPINE1. In addition, CNB001 significantly suppressed neutrophil infiltration, IL-6, TNF-α, IL-13 and active SERPINE1 production in bronchoalveolar lavage fluid of the murine asthma model, which was not observed in the case of DEX. In conclusion, the curcumin derivative, CNB001, is a promising candidate to treat asthma associated with neutrophilic airway inflammation and remodeling.

Oxidative stress induces unfolding protein response and inflammation in nasal polyposis

BACKGROUND

Nasal polyposis, a chronic inflammatory disease affecting the upper airways, is a valuable and accessible model to investigate the mechanisms underlying chronic inflammation. The main objective of this study was to investigate a potential involvement of the unfolded protein response (UPR) in the context of oxidative stress and inflammation in nasal epithelial cells from nasal polyps (NP).

METHODS

Epithelial cells from NP (n = 20) and normal mucosa (Controls, n = 15) in primary culture were analyzed by global proteomic approach and cell biology techniques for the glucose-regulated protein 78 (GRP78), the spliced X-box-binding protein 1 (sXBP-1), the glucose-regulated protein 94 (GRP94), and the calreticulin (immunoblot, mass spectrometry, immunocytochemistry).

RESULTS

Proteomics analysis of human nasal epithelial cells in culture revealed the activation of the unfolded protein response in NP. Systematic cell biology and biochemical analysis of two markers (GRP78, sXBP-1) in the presence and absence of oxidative stress in NP showed a susceptibility of the unfolded protein response to oxidative stress compared to controls at least partially linked to an abnormal redox state of the protein disulfide-isomerase 4. This unfolded protein response was correlated with mitochondrial depolarization and secretion of interleukin 8 (IL-8) and leukotriene B4 (LTB4) and was prevented by mitochondrial antioxidant.

CONCLUSIONS

We show the existence of UPR in nasal epithelial cells that is linked to oxidative stress leading to IL-8 and LTB4 secretions. These mechanisms may participate in chronic inflammation in nasal polyposis.

How the genetics of lung cancer may overlap with COPD

Over the last 30years, epidemiological studies have shown that COPD is the single most important risk factor for lung cancer after smoking exposure. Recent genetic studies using genome-wide approaches suggest that the genetic risk factors predisposing smokers to COPD and lung cancer may overlap. The genes identified by these studies suggest that this overlapping genetic susceptibility may be mediated through receptors expressed on the bronchial epithelium that implicate molecular pathways underlying both COPD and lung cancer. Furthermore, it appears that aberrant inflammatory and/or immune-modulatory pathways leading to excess matrix metalloproteinases, growth factors and airway remodelling in COPD may also be promoting malignant transformation of the bronchial epithelium. The process linking inflammation, remodelling and cancer formation is called epithelial-mesenchymal transition. There are several clinical implications arising from the COPD-lung cancer overlap. First, if COPD is a precursor disease to lung cancer then efforts to prevent COPD, might be even more important. Second, if drugs targeting the overlapping molecular pathways can be identified, chemoprevention that reduce the propensity to COPD and lung cancer is an attractive option. Finally, if low-dose computerized tomography can identify treatable lung cancer, gene-based tests of susceptibility might help identify those smokers who should undergo radiological screening.

Adjuvant immunotherapy for non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the biggest cancer killer in the United States and worldwide. In 2011, there are estimated to be 221,130 new cases of lung cancer in the United States. Over a million people will die of lung cancer worldwide this year alone. When possible, surgery to remove the tumor is the best treatment strategy for patients with NSCLC. However, even with adjuvant (postoperative) chemotherapy and radiation, more than 40% of patients will develop recurrences locally or systemically and ultimately succumb to their disease. Thus, there is an urgent need for developing superior approaches to treat patients who undergo surgery for NSCLC to eliminate residual disease that is likely responsible for these recurrences. Our group and others have been interested in using immunotherapy to augment the efficacy of current treatment strategies. Immunotherapy is very effective against minimal disease burden and small deposits of tumor cells that are accessible by the circulating immune cells. Therefore, this strategy may be ideally suited as an adjunct to surgery to seek and destroy microscopic tumor deposits that remain after surgery. This review describes the mechanistic underpinnings of immunotherapy and how it is currently being used to target residual disease and prevent postoperative recurrences after pulmonary resection in NSCLC.

Expression of B-RAF V600E in type II pneumocytes causes abnormalities in alveolar formation, airspace enlargement and tumor formation in mice

Growth factor induced signaling cascades are key regulatory elements in tissue development, maintenance and regeneration. Perturbations of these cascades have severe consequences, leading to developmental disorders and neoplastic diseases. As a major function in signal transduction, activating mutations in RAF family kinases are the cause of human tumorigenesis, where B-RAF V600E has been identified as the prevalent mutant. In order to address the oncogenic function of B-RAF V600E, we have generated transgenic mice expressing the activated oncogene specifically in lung alveolar epithelial type II cells. Constitutive expression of B-RAF V600E caused abnormalities in alveolar epithelium formation that led to airspace enlargements. These lung lesions showed signs of tissue remodeling and were often associated with chronic inflammation and low incidence of lung tumors. The inflammatory cell infiltration did not precede the formation of the lung lesions but was rather accompanied with late tumor development. These data support a model where the continuous regenerative process initiated by oncogenic B-RAF-driven alveolar disruption provides a tumor-promoting environment associated with chronic inflammation.

Quantitative CT assessment of emphysema and airways in relation to lung cancer risk

PURPOSE

To determine whether quantitative computed tomographic (CT) measurements of emphysema and airway dimensions are associated with lung cancer risk in a screening population.

MATERIALS AND METHODS

Institutional review board approval and informed consent for the use of deidentified images were obtained. In this retrospective study, CT scans were analyzed from 279 participants in the CT screening arm of the National Lung Screening Trial who were diagnosed with lung cancer and 279 participants who were not diagnosed with lung cancer after a median follow-up period of 6.6 years. Quantitative CT measurements of emphysema and right upper lobe apical segmental and subsegmental airway dimensions, and multiple patient history-related variables, were compared between the two groups. Significant variables were tested in multivariate models for association with lung cancer by using multiple logistic regression.

RESULTS

The emphysema index of percentage upper lung volume less than -950 HU had the strongest association with lung cancer (mean, 10.7% [standard deviation, 13.5] in patients vs 7.2% [standard deviation, 10.4] in control subjects; P < .001), but the relationship was weak (R(2) = 0.015, P < .001, c = 0.57). No CT measures of emphysema had an association with lung cancer independent of the patient medical history variables. Airway dimensions were not associated with lung cancer.

CONCLUSION

Quantitative CT measurements of emphysema but not airway dimensions were only weakly associated with lung cancer, demonstrating no potential practical value for clinical risk stratification.

The First Type III Domain of Fibronectin is Associated with the Expression of Cytokines within the Lung Tumor Microenvironment

Recent studies have pointed to changes in tissue mechanics as a contributory element to the development of malignancies. Increased tissue rigidity is associated with the unfolding of the Type III domains of fibronectin within the extracellular matrix. The consequences of this unfolding on cellular functions within the lung are not well understood. In the present study, we evaluated the effect of a peptide representing a partially unfolded intermediate of the first Type III repeat of fibronectin (FnIII-1c) on inflammatory gene expression in adult human lung fibroblast cells. FnIII-1c induced expression of cytokines, CXCL1-3, IL-8 and TNF-α, by lung fibroblast cells. The increase in IL-8 expression was dependent on Toll-like receptor 2 and NFκB. Immunohistochemistry of tissue arrays representing squamous cell carcinoma of the lung revealed extensive stromal staining for IL-8 and fibronectin fibrils which were co-aligned with myofibroblasts. These data suggest a model in which unfolding of FnIII domains secondary to myofibroblast-generated tension may induce the release of cytokines by stromal fibroblasts present within the lung tumor.

GSTM1 null genotype in COPD and lung cancer: evidence of a modifier or confounding effect?

Background

Studies over the past two decades have reported associations between GSTM1 (glutathione S-transferase mu 1) null genotype and chronic obstructive pulmonary disease (COPD) or lung cancer. However, a modifier or confounding effect from COPD mediating the GSTM1 association with lung cancer has not been previously explored.

Aim and methods

This variant was examined in a case-control study of current or former smokers with COPD (n = 669), lung cancer (n = 454), or normal lung function (n = 488). Sex, age, and smoking history were comparable between groups.

Results

The GSTM1 null genotype was found to be more frequent in smokers with COPD alone (odds ratio [OR] 1.30, 95% confidence interval [CI] 1.02–1.66, P = 0.031) and lung cancer (OR 1.26, 95% CI 0.96–1.65, P = 0.083) than in matched smokers with normal lung function (62%, 61%, and 56%, respectively). However, when smokers with lung cancer were subgrouped according to the presence of COPD, then the association with all COPD subjects (OR 1.34, 95% CI 1.07–1.70, P = 0.010) and with COPD and lung cancer (OR 1.50, 95% CI 1.06–2.12, P = 0.018) continued to be significant while that with lung cancer only was reduced (OR 1.11, 95% CI 0.78–1.56, P = 0.55). These associations were independent of age, sex, height, lung function, and smoking history.

Conclusion

Findings suggest that COPD is an important subphenotype of lung cancer and may underlie previously reported associations with the GSTM1 null genotype.

Early assessment of cancer outcomes in New York City firefighters after the 9/11 attacks: an observational cohort study

BACKGROUND

The attacks on the World Trade Center (WTC) on Sept 11, 2001 (9/11) created the potential for occupational exposure to known and suspected carcinogens. We examined cancer incidence and its potential association with exposure in the first 7 years after 9/11 in firefighters with health information before 9/11 and minimal loss to follow-up.

METHODS

We assessed 9853 men who were employed as firefighters on Jan 1, 1996. On and after 9/11, person-time for 8927 firefighters was classified as WTC-exposed; all person-time before 9/11, and person-time after 9/11 for 926 non-WTC-exposed firefighters, was classified as non-WTC exposed. Cancer cases were confirmed by matches with state tumour registries or through appropriate documentation. We estimated the ratio of incidence rates in WTC-exposed firefighters to non-exposed firefighters, adjusted for age, race and ethnic origin, and secular trends, with the US National Cancer Institute Surveillance Epidemiology and End Results (SEER) reference population. CIs were estimated with overdispersed Poisson models. Additional analyses included corrections for potential surveillance bias and modified cohort inclusion criteria.

FINDINGS

Compared with the general male population in the USA with a similar demographic mix, the standardised incidence ratios (SIRs) of the cancer incidence in WTC-exposed firefighters was 1·10 (95% CI 0·98-1·25). When compared with non-exposed firefighters, the SIR of cancer incidence in WTC-exposed firefighters was 1·19 (95% CI 0·96-1·47) corrected for possible surveillance bias and 1·32 (1·07-1·62) without correction for surveillance bias. Secondary analyses showed similar effect sizes.

INTERPRETATION

We reported a modest excess of cancer cases in the WTC-exposed cohort. We remain cautious in our interpretation of this finding because the time since 9/11 is short for cancer outcomes, and the reported excess of cancers is not limited to specific organ types. As in any observational study, we cannot rule out the possibility that effects in the exposed group might be due to unidentified confounders. Continued follow-up will be important and should include cancer screening and prevention strategies.

FUNDING

National Institute for Occupational Safety and Health.

Genetic evidence linking lung cancer and COPD: a new perspective

Epidemiological studies indicate that tobacco smoke exposure accounts for nearly 90% of cases of chronic obstructive pulmonary disease (COPD) and lung cancer. However, genetic factors may explain why 10%–30% of smokers develop these complications. This perspective reviews the evidence suggesting that COPD is closely linked to susceptibility to lung cancer and outlines the potential relevance of this observation. Epidemiological studies show that COPD is the single most important risk factor for lung cancer among smokers and predates lung cancer in up to 80% of cases. Genome-wide association studies of lung cancer, lung function, and COPD have identified a number of overlapping “susceptibility” loci. With stringent phenotyping, it has recently been shown that several of these overlapping loci are independently associated with both COPD and lung cancer. These loci implicate genes underlying pulmonary inflammation and apoptotic processes mediated by the bronchial epithelium, and link COPD with lung cancer at a molecular genetic level. It is currently possible to derive risk models for lung cancer that incorporate lung cancer-specific genetic variants, recently identified “COPD-related” genetic variants, and clinical variables. Early studies suggest that single nucleotide polymorphism-based risk stratification of smokers might help better target novel prevention and early diagnostic strategies in lung cancer.

Interaction of cigarette exposure and airway epithelial cell gene expression

Cigarette smoking is responsible for lung cancer and chronic obstructive pulmonary disease (COPD), the leading cause of death from cancer and the second-leading cause of death in the United States. In the United States, 46 million people smoke, with an equal number of former smokers. Moreover, 20-25% of current or former smokers will develop either disease, and smokers with one disease are at increased risk for developing the other. There are no tools for predicting risk of developing either disease; no accepted tools for early diagnosis of potentially curable lung cancer; and no tools for defining molecular pathways or molecular subtypes of these diseases, for predicting rate of progression, or for assessing response to therapy at a biochemical or molecular level. This review discusses current studies and the future potential of measuring global gene expression in epithelial cells that are in the airway field of injury and of using the genomic information derived to begin to answer some of the above questions.

Dissecting DNA hypermethylation in cancer

There is compelling evidence to support the importance of DNA methylation alterations in cancer development. Both losses and gains of DNA methylation are observed, thought to contribute pathophysiologically by inactivating tumor suppressor genes, inducing chromosomal instability and ectopically activating gene expression. Lesser known are the causes of aberrant DNA methylation. Recent studies have pointed out that intrinsic gene susceptibility to DNA methylation, environmental factors and gene function all have an intertwined participation in this process. Overall, these data support a deterministic rather than a stochastic mechanism for de novo DNA methylation in cancer. In this review article, we discuss the technologies available to study DNA methylation and the endogenous and exogenous factors that influence the onset of de novo methylation in cancer.

Neutrophilic airways inflammation in lung cancer: the role of exhaled LTB-4 and IL-8

BACKGROUND

Recent advances in lung cancer biology presuppose its inflammatory origin. In this regard, LTB-4 and IL-8 are recognized to play a crucial role in neutrophil recruitment into airways during lung cancer.Notwithstanding the intriguing hypothesis, the exact role of neutrophilic inflammation in tumour biology remains complex and not completely known.The aim of this study was to give our contribution in this field by investigating LTB-4 and IL-8 in the breath condensate of NSCLC patients and verifying their role in cancer development and progression.

METHOD

We enrolled 50 NSCLC patients and 35 controls. LTB-4 and IL-8 concentrations were measured in the breath condensate and the blood of all the subjects under study using EIA kits. Thirty NSCLC patients and ten controls underwent induced sputum collection and analysis.

RESULTS

LTB-4 and IL-8 resulted higher in breath condensate and the blood of NSCLC patients compared to controls. Significantly higher concentrations were found as the cancer stages progressed. A positive correlation was observed between exhaled IL-8 and LTB-4 and the percentage of neutrophils in the induced sputum.

CONCLUSION

The high concentrations of exhaled LTB-4 and IL-8 showed the presence of a neutrophilic inflammation in the airways of NSCLC patients and gave a further support to the inflammatory signalling in lung cancer. These exhaled proteins could represent a suitable non-invasive marker in the diagnosis and monitoring of lung cancer.

IL-17RA is required for CCL2 expression, macrophage recruitment, and emphysema in response to cigarette smoke

Chronic Obstructive Pulmonary Disease (COPD) is characterized by airspace enlargement and peribronchial lymphoid follicles; however, the immunological mechanisms leading to these pathologic changes remain undefined. Here we show that cigarette smoke is a selective adjuvant that augments in vitro and in vivo Th17, but not Th1, cell differentiation via the aryl hydrocarbon receptor. Smoke exposed IL-17RA(-/-) mice failed to induce CCL2 and MMP12 compared to WT mice. Remarkably, in contrast to WT mice, IL-17RA(-/-) mice failed to develop emphysema after 6 months of cigarette smoke exposure. Taken together, these data demonstrate that cigarette smoke is a potent Th17 adjuvant and that IL-17RA signaling is required for chemokine expression necessary for MMP12 induction and tissue emphysema.

Lung cancer risk prediction: Prostate, Lung, Colorectal And Ovarian Cancer Screening Trial models and validation

INTRODUCTION

Identification of individuals at high risk for lung cancer should be of value to individuals, patients, clinicians, and researchers. Existing prediction models have only modest capabilities to classify persons at risk accurately.

METHODS

Prospective data from 70 962 control subjects in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) were used in models for the general population (model 1) and for a subcohort of ever-smokers (N = 38 254) (model 2). Both models included age, socioeconomic status (education), body mass index, family history of lung cancer, chronic obstructive pulmonary disease, recent chest x-ray, smoking status (never, former, or current), pack-years smoked, and smoking duration. Model 2 also included smoking quit-time (time in years since ever-smokers permanently quit smoking). External validation was performed with 44 223 PLCO intervention arm participants who completed a supplemental questionnaire and were subsequently followed. Known available risk factors were included in logistic regression models. Bootstrap optimism-corrected estimates of predictive performance were calculated (internal validation). Nonlinear relationships for age, pack-years smoked, smoking duration, and quit-time were modeled using restricted cubic splines. All reported P values are two-sided.

RESULTS

During follow-up (median 9.2 years) of the control arm subjects, 1040 lung cancers occurred. During follow-up of the external validation sample (median 3.0 years), 213 lung cancers occurred. For models 1 and 2, bootstrap optimism-corrected receiver operator characteristic area under the curves were 0.857 and 0.805, and calibration slopes (model-predicted probabilities vs observed probabilities) were 0.987 and 0.979, respectively. In the external validation sample, models 1 and 2 had area under the curves of 0.841 and 0.784, respectively. These models had high discrimination in women, men, whites, and nonwhites.

CONCLUSION

The PLCO lung cancer risk models demonstrate high discrimination and calibration.

Lung dysfunction of chronic smokers with no signs of COPD

Cigarette smoking causes airflow limitation with lung hyperinflation being the primary causes of COPD. Fifty chronic smokers (CSs) with no signs of GOLD-adjusted COPD with smoking habit at least ≥10 pack-years (p/yrs) were divided into CS-mild (n = 24) with smoking history from ≥10 to ≤20 p/yrs and CS-heavy groups (n = 26) with smoking history ≥21 p/yrs. Spirometry, plethysmography and diffusing capacity were measured and lung computed tomography (CT) was performed. Residual volume (RV) (L) and RV/TLC (total lung capacity) ratio were significantly increased in CS-heavy when compared to CS-mild (p = 0.001, p = 0.03). A significant reduction of forced expiratory volume in 1 second/forced vital capacity (FEV(1)/FVC) ratio and airway specific conductance was shown in CS-heavy (p = 0.02, p = 0.03). Lung emphysema signs at CTs were revealed in 17 CSs and ten of them had declined diffusing capacity below 70% of predicted. The percentage of emphysematous lesions inversely and significantly correlated with measured diffusing capacity (p = 0.0009, r = --0.72). Study groups' smoking intensity inversely correlated the declined airway specific conductance (p = 0.004, r = --0.39) and increase of the RV (L) (p = 0.0004, r = 0.46). Multiple regression analysis determined that smoking intensity regardless of the subjects' age was significant factor for decline of airway specific conductance and increase of RV (L). Here we conclude that lung function deviation and lung structural changes are present in CSs before the clinical signs of airway obstruction reveal. Body plethysmography and diffusing capacity measurement with routine spirometry can provide valuable information for detection of changes reflecting to the early onset of COPD in CSs.

Origins of injection-site sarcomas in cats: the possible role of chronic inflammation-a review

The etiology of feline injection-site sarcomas remains obscure. Sarcomas and other tumors are known to be associated with viral infections in humans and other animals, including cats. However, the available evidence suggests that this is not the case with feline injection-site sarcomas. These tumors have more in common with sarcomas noted in experimental studies with laboratory animals where foreign materials such as glass, plastics, and metal are the causal agent. Tumors arising with these agents are associated with chronic inflammation at the injection or implantation sites. Similar tumors have been observed, albeit infrequently, at microchip implantation sites, and these also are associated with chronic inflammation. It is suggested that injection-site sarcomas in cats may arise at the administration site as a result of chronic inflammation, possibly provoked by adjuvant materials, with subsequent DNA damage, cellular transformation, and clonal expansion. However, more fundamental research is required to elucidate the mechanisms involved.

Epigenetic mechanisms in inflammation

Epigenetic modifications occur in response to environmental changes and play a fundamental role in gene expression following environmental stimuli. Major epigenetic events include methylation and acetylation of histones and regulatory factors, DNA methylation, and small non-coding RNAs. Diet, pollution, infections, and other environmental factors have profound effects on epigenetic modifications and trigger susceptibility to diseases. Despite a growing body of literature addressing the role of the environment on gene expression, very little is known about the epigenetic pathways involved in the modulation of inflammatory and anti-inflammatory genes. This review summarizes the current knowledge about epigenetic control mechanisms during the inflammatory response.

Individual and cumulative effects of GWAS susceptibility loci in lung cancer: associations after sub-phenotyping for COPD

Epidemiological studies show that approximately 20–30% of chronic smokers develop chronic obstructive pulmonary disease (COPD) while 10–15% develop lung cancer. COPD pre-exists lung cancer in 50–90% of cases and has a heritability of 40–77%, much greater than for lung cancer with heritability of 15–25%. These data suggest that smokers susceptible to COPD may also be susceptible to lung cancer. This study examines the association of several overlapping chromosomal loci, recently implicated by GWA studies in COPD, lung function and lung cancer, in (n = 1400) subjects sub-phenotyped for the presence of COPD and matched for smoking exposure. Using this approach we show; the 15q25 locus confers susceptibility to lung cancer and COPD, the 4q31 and 4q22 loci both confer a reduced risk to both COPD and lung cancer, the 6p21 locus confers susceptibility to lung cancer in smokers with pre-existing COPD, the 5p15 and 1q23 loci both confer susceptibility to lung cancer in those with no pre-existing COPD. We also show the 5q33 locus, previously associated with reduced FEV₁, appears to confer susceptibility to both COPD and lung cancer. The 6p21 locus previously linked to reduced FEV₁ is associated with COPD only. Larger studies will be needed to distinguish whether these COPD-related effects may reflect, in part, associations specific to different lung cancer histology. We demonstrate that when the “risk genotypes” derived from the univariate analysis are incorporated into an algorithm with clinical variables, independently associated with lung cancer in multivariate analysis, modest discrimination is possible on receiver operator curve analysis (AUC = 0.70). We suggest that genetic susceptibility to lung cancer includes genes conferring susceptibility to COPD and that sub-phenotyping with spirometry is critical to identifying genes underlying the development of lung cancer.

Common pathogenic mechanisms and pathways in the development of COPD and lung cancer

INTRODUCTION

Lung cancer and COPD commonly coexist in smokers, and the presence of COPD increases the risk of developing lung cancer. In addition to smoking cessation and preventing smoking initiation, understanding the shared mechanisms of these smoking-related lung diseases is critical, in order to develop new methods of prevention, diagnosis and treatment of lung cancer and COPD.

AREAS COVERED

This review discusses the common mechanisms for susceptibility to lung cancer and COPD, which in addition to cigarette smoke, may involve inflammation, epithelial-mesenchymal transition, abnormal repair, oxidative stress, and cell proliferation. Furthermore, we discuss the underlying genomic and epigenomic changes (single nucleotide polymorphisms (SNPs), copy number variation, promoter hypermethylation and microRNAs) that are likely to alter biological pathways, leading to susceptibility to lung cancer and COPD (e.g., altered nicotine receptor biology).

EXPERT OPINION

Strategies to study genomics, epigenomics and gene-environment interaction will yield greater insight into the shared pathogenesis of lung cancer and COPD, leading to new diagnostic and therapeutic modalities.

FAM13A locus in COPD is independently associated with lung cancer - evidence of a molecular genetic link between COPD and lung cancer

Recent genome-wide association studies have reported a FAM13A variant on chromosome 4q22.1 is associated with lung function and COPD. We examined this variant in a case-control study of current or former smokers with chronic obstructive pulmonary disease (COPD, n = 458), lung cancer (n = 454), or normal lung function (n = 488). Sex, age, and smoking history were comparable between groups. We confirmed the FAM13A variant (rs7671167) confers a protective effect on smoking-related COPD alone (C allele odds ratio [OR] = 0.79, P = 0.013, and CC genotype OR = 0.71, P = 0.024) and those with COPD, both with and without lung cancer (C allele OR = 0.80, P = 0.008, and CC genotype OR = 0.70, P = 0.007). The FAM13A variant also confers a protective effect on lung cancer overall (C allele OR = 0.75, P = 0.002, and CC genotype OR = 0.64, P = 0.003) even after excluding those with co-existing COPD (C allele OR = 0.67, P = 0.0007, and CC genotype OR = 0.58, P = 0.006). This was independent of age, sex, height, lung function, and smoking history. This protective effect was confined to those with nonsmall cell lung cancer (C allele OR = 0.72, P = 0.0009, and CC genotype OR = 0.61, P = 0.003). This study suggests that genetic predisposition to COPD is shared with lung cancer through shared pathogenetic factors such as the 4q22.1 locus implicating the Rho-kinase pathway.

Cigarette smoking, cyclooxygenase-2 pathway and cancer

Cigarette smoking is a major cause of mortality and morbidity worldwide. Cyclooxygenase (COX) and its derived prostanoids, mainly including prostaglandin E2 (PGE2), thromboxane A2 (TxA2) and prostacyclin (PGI2), have well-known roles in cardiovascular disease and cancer, both of which are associated with cigarette smoking. This article is focused on the role of COX-2 pathway in smoke-related pathologies and cancer. Cigarette smoke exposure can induce COX-2 expression and activity, increase PGE2 and TxA2 release, and lead to an imbalance in PGI2 and TxA2 production in favor of the latter. It exerts pro-inflammatory effects in a PGE2-dependent manner, which contributes to carcinogenesis and tumor progression. TxA2 mediates other diverse biologic effects of cigarette smoking, such as platelet activation, cell contraction and angiogenesis, which may facilitate tumor growth and metastasis in smokers. Among cigarette smoke components, nicotine and its derived nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) are the most potent carcinogens. COX-2 and PGE2 have been shown to play a pivotal role in many cancers associated with cigarette smoking, including cancers of lung, gastric and bladder, while the information for the role of TxA2 and PGI2 in smoke-associated cancers is limited. Recent findings from our group have revealed how NNK influences the TxA2 to promote the tumor growth. Better understanding in the above areas may help to generate new therapeutic protocols or to optimize the existing treatment strategy.

Inflammation and cancer: macrophage migration inhibitory factor (MIF)--the potential missing link

Macrophage migration inhibitory factor (MIF) was the original cytokine, described almost 50 years ago and has since been revealed to be an important player in pro-inflammatory diseases. Recent work using MIF mouse models has revealed new roles for MIF. In this review, we present an increasing body of evidence implicating the key pro-inflammatory cytokine MIF in specific biological activities related directly to cancer growth or contributing towards a microenvironment favouring cancer progression.

Smoking cessation and lung cancer risk in an Asian population: findings from the Singapore Chinese Health Study

Background:

Smoking cessation is an important strategy for reducing the harmful effects of tobacco, particularly in the prevention of lung cancer; however, prospective data on the impact of smoking cessation on lung cancer risk in Asian populations are limited.

Methods:

We studied a population-based cohort of Chinese men and women aged 45–74 years – participants of the Singapore Chinese Health Study. Information on smoking, lifestyle and dietary habits was collected at the time of recruitment in 1993–1998; and smoking status was assessed again at a second interview in 1999–2004 (mean interval 5.8 years). Participants were followed up to 31 December 2007, and incident cases of lung cancer were ascertained by linkage with population-wide registries.

Results:

Among 45 900 participants, there were 463 incident cases of lung cancer. Relative to current smokers, those who quit smoking subsequent to baseline assessment had a 28% decrease in the risk of lung cancer (adjusted hazard ratio (HR) 0.72; 95% CI (95% confidence interval): 0.53–0.98). The risk was less than half in ex-smokers who had quit before the first interview and maintained their status (HR 0.42; 95% CI: 0.32–0.56).

Conclusions:

Reduction in lung cancer incidence with smoking cessation in Asian populations is substantial and can be observed within a few years after quitting.

Cigarette smoking reprograms apical junctional complex molecular architecture in the human airway epithelium in vivo

The apical junctional complex (AJC), composed of tight and adherens junctions, maintains epithelial barrier function. Since cigarette smoking and chronic obstructive pulmonary disease (COPD), the major smoking-induced disease, are associated with increased lung epithelial permeability, we hypothesized that smoking alters the transcriptional program regulating airway epithelial AJC integrity. Transcriptome analysis revealed global down-regulation of physiological AJC gene expression in the airway epithelium of healthy smokers (n = 59) compared to nonsmokers (n = 53) in association with changes in canonical epithelial differentiation pathways such as PTEN signaling accompanied by induction of cancer-related AJC components. The overall expression of AJC-related genes was further decreased in COPD smokers (n = 23). Exposure of airway epithelial cells to cigarette smoke extract in vitro resulted in down-regulation of several AJC genes paralleled by decreased transepithelial resistance. Thus, cigarette smoking induces transcriptional reprogramming of airway epithelial AJC architecture from its physiological pattern necessary for barrier function toward a disease-associated molecular phenotype.

Development of autoantibody signatures as novel diagnostic biomarkers of non-small cell lung cancer

PURPOSE

To select autoantibody signatures as noninvasive biomarkers of non-small cell lung cancer (NSCLC).

EXPERIMENTAL DESIGN

A phage cDNA expression library was constructed with fresh samples from 30 lung cancer patients and biopanned using serum pools of 10 NSCLC patients and 10 healthy controls. A six-phage peptide detector was discovered by two-step immunoscreenings and was validated in an independent set of 90 NSCLC patients and 90 matched healthy controls, 30 NSCLC patients with chemotherapy, and 12 chronic obstructive pulmonary disease (COPD) patients. The expression of a peptide target was validated by using immunohistochemistry. Factors affecting NSCLC-related death were evaluated by Cox regression analysis.

RESULTS

Six phage peptide clones showing higher seroreactivity than others in 30 NSCLC patients were selected for diagnostic validation. The six-phage peptide detector was able to discriminate between NSCLC patients and healthy controls with a sensitivity and specificity of >92%, and had similar validity for indicating NSCLC at early stage. The seroreactivity of the six phage peptides was significantly higher in the NSCLC patients than in those with chemotherapy and the COPD patients, respectively. Of the six phage peptides, one encoded a peptide showing 100% homology to olfactomedin 1. Expression of olfactomedin 1 protein was significantly higher in lung adenocarcinoma than in lung cancer of other histologic types and normal lung tissues. The autoantibody signature was not associated with the prognosis of the NSCLC patients.

CONCLUSIONS

The six-phage peptide detector stands out as promising diagnostic biomarkers for NSCLC, unlikely for NSCLC relapse after chemotherapy. Olfactomedin 1 may be a novel target of lung adenocarcinoma.

Are airflow obstruction and radiographic evidence of emphysema risk factors for lung cancer? A nested case-control study using quantitative emphysema analysis

OBJECTIVES

Several studies have identified airflow obstruction as a risk factor for lung cancer independent of smoking history, but the risk associated with the presence of radiographic evidence of emphysema has not been extensively studied. We proposed to assess this risk using a quantitative volumetric CT scan analysis.

METHODS

Sixty-four cases of lung cancer were identified from a prospective cohort of 1,520 participants enrolled in a spiral CT scan lung cancer screening trial. Each case was matched to six control subjects for age, sex, and smoking history. Quantitative CT scan analysis of emphysema was performed. Spirometric measures were also conducted. Data were analyzed using conditional logistic regression making use of the 1:6 set groups of 64 cases and 377 matched control subjects.

RESULTS

Decreased FEV(1) and FEV(1)/FVC were significantly associated with a diagnosis of lung cancer with ORs of 1.15 (95% CI, 1.00-1.32; P = .046) and 1.29 (95% CI, 1.02-1.62; P = .031), respectively. The quantity of radiographic evidence of emphysema was not found to be a significant risk for lung cancer with OR of 1.042 (95% CI, 0.816-1.329; P = .743). Additionally, there was no significant association between severe emphysema and lung cancer with OR of 1.57 (95% CI, 0.73-3.37).

CONCLUSIONS

We confirm previous observations that airflow obstruction is an independent risk factor for lung cancer. The absence of a clear relationship between radiographic evidence of emphysema and lung cancer using an automated quantitative volumetric analysis may result from different population characteristics than those of prior studies, radiographic evidence of emphysema quantitation methodology, or absence of any relationship between emphysema and lung cancer risk.

The detection of chromosomal aneusomy by fluorescence in situ hybridization in sputum predicts lung cancer incidence

Lung cancer usually is disseminated (advanced) and has a poor prognosis at diagnosis. Current and former smokers are at a high risk for lung cancer and are candidates for prevention and early detection strategies. Sputum is a potential source of biomarkers that might determine either lung cancer risk or the presence of early lung cancer, but no current sputum test is sufficiently sensitive and specific for effective screening. We used fluorescence in situ hybridization (FISH) to measure chromosomal aneusomy (CA) in sputum samples collected prospectively from 100 incident lung cancer cases and 96 controls (matched on age, gender, and date of collection) nested within an ongoing high-risk cohort. The CA-FISH assay was aimed at four DNA targets: epidermal growth factor receptor, MYC, 5p15, and CEP 6. The sensitivity of a positive CA-FISH assay (abnormal for two or more of the four markers) for lung cancer was substantially higher for samples collected within 18 months (76% sensitivity) than for samples collected more than 18 months (31%) before lung cancer diagnosis. Sensitivity was higher for squamous cell cancers (94%) than for other histologic types (69%). CA-FISH specificity based on samples collected within 18 months before diagnosis was 88%. The adjusted odds ratio (OR) of lung cancer for specimens collected within 18 months before a cancer diagnosis was higher for the CA-FISH assay [OR, 29.9; 95% confidence interval (95% CI), 9.5-94.1] than for previously studied ORs of cytologic atypia (OR, 1.8; 95% CI, 1.3-2.6) and gene promoter methylation (OR, 6.5; 95% CI, 1.2-35.5). Whether CA-FISH is an indicator of extreme risk for incident lung cancer or detects exfoliated cancer cells is unknown. The apparent promise of CA-FISH in sputum for assessing lung cancer risk and/or for lung cancer early detection now needs to be validated in a clinical screening trial.

Epithelial-mesenchymal transition in primary human bronchial epithelial cells is Smad-dependent and enhanced by fibronectin and TNF-alpha

Background

Defective epithelial repair, excess fibroblasts and myofibroblasts, collagen overproduction and fibrosis occur in a number of respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis. Pathological conversion of epithelial cells into fibroblasts (epithelial-mesenchymal transition, EMT) has been proposed as a mechanism for the increased fibroblast numbers and has been demonstrated to occur in lung alveolar epithelial cells. Whether other airway cell types also have the capability to undergo EMT has been less explored so far. A better understanding of the full extent of EMT in airways, and the underlying mechanisms, can provide important insights into airway disease pathology and enable the development of new therapies. The main aim of this study was to test whether primary human bronchial epithelial cells are able to undergo EMT in vitro and to investigate the effect of various profibrotic factors in the process.

Results

Our data demonstrate that primary human bronchial epithelial cells (HBECs) are able to undergo EMT in response to transforming growth factor-beta 1 (TGF-β1), as revealed by typical morphological alterations and EMT marker progression at the RNA level by real-time quantitative polymerase chain reaction and, at the protein level, by western blot. By using pharmacological inhibitors we show that this is a Smad-dependent mechanism and is independent of extracellular signal-related kinase pathway activation. Additional cytokines and growth factors such as tumour necrosis factor-alpha (TNF-α), interleukin-1 beta (IL1β) and connective tissue growth factor (CTGF) were also tested, alone or in combination with TGF-β1. TNF-α markedly enhances the effect of TGF-β1 on EMT, whereas IL1β shows only a very weak effect and CTGF has no significant effect. We have also found that cell-matrix contact, in particular to fibronectin, an ECM component upregulated in fibrotic lesions, potentiates EMT in both human alveolar epithelial cells and HBECs. Furthermore, we also show that the collagen discoidin domain receptor 1 (DDR1), generally expressed in epithelial cells, is downregulated during the EMT of bronchial epithelium whereas DDR2 is unaffected. Our results also suggest that bone morphogenetic protein-4 is likely to have a context dependent effect during the EMT of HBECs, being able to induce the expression of EMT markers and, at the same time, to inhibit TGF-β induced epithelial transdifferentiation.

Conclusions

The results presented in this study provide additional insights into EMT, a potentially very important mechanism in fibrogenesis. We show that, in addition to alveolar epithelial type II cells, primary HBECs are also able to undergo EMT in vitro upon TGF-β1 stimulation via a primarily Smad 2/3 dependent mechanism. The effect of TGF-β1 is potentiated on fibronectin matrix and in the presence of TNF-α, representing a millieu reminiscent of fibrotic lesions. Our results can contribute to a better understanding of lung fibrosis and to the development of new therapeutic approaches.

The molecular and cellular biology of lung cancer: identifying novel therapeutic strategies

INTRODUCTION

Lung cancer is the commonest fatal malignancy in the developed world. Survival rates for lung cancer have not changed significantly over the past 30 years. Sources of data This report is a systematic review of the literature on our current understanding of lung cancer biology. Searches were carried out using PUBMED. 1990-2010.

AREAS OF AGREEMENT

A concerted effort to reduce cigarette smoking and nicotine addiction is required. A better understanding of the biology of lung cancer will lead to the identification of earlier diagnostic markers and improved therapy.

AREAS OF CONTROVERSY

How chronic inflammatory disorders such as COPD and lung fibrosis contribute to lung cancer development is incompletely understood.

GROWING POINTS

Developing novel biological agents to target lung cancer. New microarray-based technologies provide new methods for predicting prognosis and response to treatment.

AREAS TIMELY FOR DEVELOPING RESEARCH

Developing strategies to target lung cancer stem cells may provide a novel approach for treating drug resistant disease.